58

of every exhibitor are largely contaminated with copper, and ought not, therefore, to be eaten."

It would be interesting to know how the "colouring material from vegetables and green foliage" is procured and used by Messrs. Batty and Co. Our pickle manufacturers may take a hint from the French, who, says the Report, "have a habit of setting off the colour of the pickles by the aid of bottles of a brilliant grass green. It is a matter for consideration whether this practice is or is not deserving of imitation in this country.'

Our concluding extract gives a description of two new processes, of which we gave some account in our notices of the Exhibition, but which is here given in greater detail:

"Preserved Meats.

"Very little improvement has been made in this branch of industry since the Exhibition of 1851, notwithstanding the importance of it, and the large increase of its trade. Most of the meat is overdone, and is loaded with fat, and in many cases the food had acquired a metallic flavour from the vessel in which it was preserved.

"As in 1851, the principal mode of preserving the meat is by the exclusion of atmospheric air. This is accomplished by first filling the case with the meat or soup, then soldering down the cover, which has a small aperture in it for the exit of steam. The cases are then stood in a saline bath, or upon a hot plate, until the liquid within them boils freely and expels the contained air. While thus boiling, and steam is freely issuing from the minute orifice in the cover, the hole is stopped with solder, and so the case is hermetically sealed. By this process the meat is generally overdone; it loses its fresh flavour, and becomes sodden and broken up; besides which, on the cooling of the case, the steam within it condenses, and there is a constant vacuum and liability to indent and buckle from atmospheric pressure. A trace, also, of air frequently remains within the case, and thus the oxygen slowly but surely sets in putrefactive decomposition. To remedy these defects two improvements have been suggested. One of these was patented by Messrs. John McCall and Co., of Houndsditch, in 1861. It consists in the introduction into the tin of a small quantity of the sulphite of soda. The proportion used is about twelve grains to each pound of meat.

The effect of this salt is to absorb from the meat and the air of the case the small proportion of free oxygen which, under the best of circumstances, often remains within it. In order that the sulphite of soda shall be isolated until the air is expelled and the case soldered down, the salt is enclosed in a tin capsule soldered to the inside of the top of the canister. The capsule has two holes in it, plugged with fusible metal, which melts at a few degrees above the temperature of boiling water (about 218°). As soon as the steaming hole is closed, and the temperature raised by the steam pressure within, the fusible metal melts and releases the sulphite of soda within the capsule. It is presumed that the effect of this improvement will be the doing away with the necessity for the prolonged steaming of the food before the cases are soldered down, and thus the prevention of that overcooking which has hitherto been so objectionable. In the case of soups, the salt is not always enclosed in a cap, but is put into the soup.

"The other improvement is a process of Messrs. Jones and Trevethick, of Botolph Lane. It provides for the preservation of food in the raw state, without the disadvantage which all preceding processes have of maintaining a vacuum within the case. The process is conducted in the following way :-The meat is wrapped up in a piece of cloth, and is enclosed in a tin case; the cover of the case is then soldered down. From the top of the case there projects a short tube which is brought into connection with the exhausting power of an air-pump-a very ingenious contrivance is adopted whereby the tin cases are protected from external pressure during exhaustion. This is accomplished by placing the tins in an air-tight vessel

{CHEMICAL NEWE

Jan. 31, 1863.

filled with water, the inelastic property of which supports the sides of the case, and prevents the slightest collapse. When the air has been exhausted from the tins, a charge of pure nitrogen is let into them. This also is exhausted, and then a minute dose of gaseous sulphurous acid is introduced. Finally, another charge of nitrogen is let in, and the vessels are permanently soldered down. The effect of the sulphurous acid is to combine with the minute trace of oxygen which remains in the case, and the nitrogen, by filling the case, prevents collapse from atmospheric pressure. The nitrogen is obtained pure from atmospheric air by a simple chemical process which absorbs the oxygen. Mutton, beef, hams, fish, poultry, and game were exhibited preserved in this way, and the results were remarkably successful and satisfactory. The poultry and game had the appearance of having been but an hour or two from the poulterer's. The ham and bacon were as good after many years' keeping as if they had been just cured; and, although the fresh meat had acquired a rather bright red tint from the action of the gases upon the flesh, yet the flavour was decidedly superior to that of any other kind of preserved meat. The process offers a promise of great economic value."

NOTICES OF PATENTS.

2694. Preservation of Stone, Brick, &c. W. SMITH, Stafford, Dated October 26, 1861.

THE patentee takes flint or other siliceous mineral, and reduces it to a fine state of division by calcination and grinding. With this he mixes powdered alum, or dry sulphate of alumina, and f rms the composition into a kind of paint by the addition of bituminous substances, glue, linseed oil, and turpentine. This material is applied as a coating to brick walls, stone, or stucco, and is said to afford a protection against decay and damp.

The advantage of employing soluble substances like glue and alum, or the deliquescent sulphate of alumina, to keep out the damp may well be questioned. For common purposes a useful paint might be prepared from the remaining ingredients.

2718. Composition for Igniting Lucifer Matches. M. A. MENNONS, Paris. A communication. Dated October 30, 1861. (Not proceeded with.)

THIS specification describes a mode of preparing a friction surface suitable for the ignition of non-phosphoric, or safety matches. Shellac, or a similar resin, is heated nearly to the melting point, and twice its weight of alcohol added, and well stirred, for the purpose of producing a homogeneous paste, with which one-tenth part of amorphous phosphorus in fine powder is then intimately incorporated. Whilst warm, this preparation is applied as a coating to the side of the match box, or is laid upon a suitable tablet either of pasteboard, wood, or earthenware.

This resinous varnish would constitute an excellent protection and means of attachment, since it is repellant of moisture, besides being very adhesive.

Jan. 31, 1863.

2744. Manufacture of Cast-Steel or of Homogeneous Iron. ROBERT MUSHET, Coleford. Dated November 1, 1861. For the preparation of superior qualities of cast-steel and homogeneous iron, the inventor mixes with these metals respectively a certain proportion of the alloy of iron, manganese, and titanium, with or without carbon, obtained by processes described in the specification of a former patent, No. 2637.*

2750. Preventing the Injurious Effects occasioned by Smoke, Sulphur, and the Deleterious Gases which escape from Chimney Stacks, Calcining Houses, Chemical and Other Furnaces. W. B. SMITH and W. BENNETT, Cornwall. Dated November 1, 1861. (Not proceeded with.) In this scheme for the suppression of the smoke nuisance, the inventors maintain a draught of air through the furnace by the rotation of a fan placed in the flue, and which is intended to drive forward the smoke and products of combustion; but these are not allowed to escape by the chimney until they have been passed through a series of intermediate chambers, and a diaphragm either of canvas or wire gauze.

Grants of Provisional Protection for Six Months. 3308. Louis Amand Lesage, Rue St. Appoline, Paris, "An improved method of preparing jellies and jams."Petition recorded December 10, 1862.

3375. Fedor de Wylde, Great College Street, Camden Town, London, "Improved means for the protection and preservation of lead surfaces exposed to the action of water, and for the protection of such surfaces from decomposition by atmospheric action."-A communication from Professor Dr. Henry Schwarz, Breslau, Prussia.

3468. William Edward Newton, Chancery Lane, London, "Improvements in preserving organic substances from decay."-A communication from Leonard Laureau, Rue St. Sébastien, Paris.-Petitions recorded December 29, 1862.

3312. Astley Paston Price, Lincoln's Inn Fields, London, "Improvements in the manufacture or production of blue colours."-A communication from Augustus Eisenlohr, Heidelberg, Baden.

3443. Ebenezer Stevens, Cheapside, London, "Improvements in machinery for preparing dough and paste suitable for making bread, biscuits, pastry, cakes, and similar

articles."

3465. Frederick Tolhausen, Faubourg Montmartre, Paris, "The use of petroleum or coal-oil as fuel, and also for the machinery and apparatus to be employed for this purpose."-A communication from Edward John Biddle, Faubourg Montmartre, Paris.

Invention Protected for Six Months by the Deposit

a Complete Specification.

of

67. Liveras Hull, Massachusetts, U.S., "Improvements in the treatment of ground caoutchouc, and for the purpose of rendering it elastic, or improving its elasticity, as well as imparting to such caoutchouc other useful properties."-Deposited and recorded January 8, 1863.

Notice to Proceed.

2462. Samuel Pudney, Manor Street, Clapham, Surrey, "Improvements in apparatus to be used in the manufacture of sulphuric acid."

* CHEMICAL News, vol. vii, p. 35.

CORRESPONDENCE.

Separation of Silver from Lead.

59

To the Editor of the CHEMICAL NEWS. SIR, A new process for extracting silver from lead would be, indeed, successful, to compete with that of Pattinson, now universally employed in this country. On perusing your "Notices of Patents," in the last Number of the CHEMICAL NEWS, I was surprised to observe that the repatenting of an old invention had not called forth some of the sensible remarks which usually indicate your opinion of the various novelties proposed and registered in the Patent Office.

Mr. Birkbeck must be ill-informel of metallurgical progress not to have heard of Mr. Parkes' ingenious process for extracting silver from lead by means of zinc, patented about twelve years ago, and which, though not at present in uae, has been tried on a large scale in South Wales. It is identical with the re-discovery patented again by Mr. Birkbeck.—I am, &c. WILLIAM BAKER. Lead Works, Sheffield.

To the Editor of the CHEMICAL NEWS. SIR,—In last week's Number of the CHEMICAL NEWS I find notice of a patent in the name of G. H. BirkbeckNo. 2643, October 23, 1861-" for extracting silver from lead," by the addition of a small quantity of zinc to the melted lead, agitating, allowing to cool, when the silver will be found combined with the zinc floating on the surface of the lead; the silver is then separated either by distillation or by solution in dilute acids, when the silver is left behind as a residuum.

Now, as it is but fair that the merit of any new discovery should be given to the real inventor, I beg to call your attention to the following facts:

I have no less than three patents, dated June 11, 1850, June 24, 1851, and May 1, 1852, all for the use of zinc in separating silver from lead by methods identically the same as given in Mr. Birkbeck's specification. My patents have been extensively carried out in one of the largest smelting works in Wales.

Under these circumstances, I should feel greatly obliged if you will insert this in your next Number, being anxious that my prior right to the discovery should be made known. I am, &c. Pro ALEXANDER PARKES, H. PARKES.

Birmingham.

International Medal and the Pharmaceutical Society.
To the Editor of the CHEMICAL NEWS.

SIR,-In your report of the last Pharmaceutical meeting
you do not mention that the chairman exhibited the
medal which had been awarded for the display of drugs
shown by the society. It was taken but little notice of
by the members present, I am told. Probably, each one
thought he had but little individual interest in the matter.
I wish, however, by means of the CHEMICAL NEWS, to
circular of Mr. Wyon, in which he says he has been
call the attention of the members of the society to the
granted the privilege of supplying copies of the medal,
identical with, and indistinguishable from, the originals,
to all members of a company or firm to which a medal has
been granted by the Commissioners. It would seem from
this, that each member of the society can have a medal
on the payment of one guinea to the Messrs. De la Rue,
and I dare say there are a good many who would like to
The object of the display by the society
possess one.
would then appear to be gained; for certainly the award
of a medal to the society in its corporate capacity looks
rather absurd.-I am, &c.
M. P. S.

60

MISCELLANEOUS.

PURE BREAD.

In these camel-swallowing times, if a waiter at an eatingroom were to hand a customer a piece of bread with his bare fingers, the chances are that, if the diner were an irascible man, the unfortunate wight would soon find himself in the street. If a guest at your dinner-table were to commit the same heinous offence, no doubt you would consider the crime against good breeding and cleanliness so great that it would be his last appearance at your board. And yet the hands of the two culprits were undoubtedly scrupulously clean. The bread they had touched, however, and about which we feel no disgust when handed with a fork, was prepared in a loathsome, underground den, reeking with filth and vermin; the hands with which the dough was mixed were dirty; and the exertions of handling heavy masses of leavened flour in a close, unventilated bakehouse caused the perspiration to roll off the arms and face of the workmen in streams into the trough. The board on which the dough was laid preparatory to its being fashioned into loaves, had served, but a few moments before, with a filthy sack thrown over it, as the temporary couch of a journeyman baker, to whom personal ablution was a stranger. To fill up this picture of horrors, there is one bakehouse at the West-end in which the space between the kneading-trough and the wall was used for the same purpose as those cast-iron erections which are now beginning to form inseparable adjuncts to our cab-ranks. Our readers, we are sure, are in possession of the strongest stomachs that long courses of sulphuretted hydrogen, kakodyl selenethyl, and other odoriferous compounds, can bestow on the human subject; but we think we have said enough to raise a slight disgust to ordinary shop bread. If we have not said sufficient, let them read a copy of Mr. Tremenheere's report on the condition of the journeymen bakers of the metropolis, and they will find horrors piled on horrors to such a height, that they will never eat shop-bread again. Several readers of that fatal report have abjured the baker, and now subsist entirely on home-made bread, kneaded and shaped into loaves by the fair hands of some female member of their family, instead of by the filthy paws of a journeyman baker.

But it is not every one who possesses in his family a good bread-maker, for bread-making is a talent, and cannot be acquired without a long apprenticeship. Hence, the differing qualities of home-made bread. The poor bachelor, too, who is obliged to gulp down the unsavory penny. loaves from round the corner-our pity is great for him. We were much pleased, therefore, to receive an invitation from Stevens' Bread Machinery Company, to inspect their bakehouses, lately established at Islington and Brompton. It does one's heart and stomach good to see the cleanliness with which all the operations are carried on, from the flour to the finished loaf. The establishment at Islington consists of a spacious shop, at the back of which is the machinery with which the bread is kneaded, worked by steam. This we will not describe, as Stevens' BreadMaking Machine has already been before the public for some years. Suffice it to say, that the laborious operation of kneading is accomplished by a series of claws, revolving in the trough in which the mixture of yeast, flour, and water, is contained. This portion of the building is divided from the shop by a glass partition, so that the public may see for themselves the cleanliness with which all the processes are conducted. Behind the machinery are two tiers of ovens, approached by light, iron staircases, and, above all, is the flour store. The bakery at Brompton is conducted on a precisely similar plan, and the inhabitants of these favoured localities are enabled to procure a constant supply of pure bread. Although we do not generally approve of joint-stock companies

CHEMICAL NEWS, Jan. 31, 1863.

entering into trade, we must confess that, in this instance, an inestimable advantage will be conferred on the public at large by the establishment of a few large concerns of this sort in different parts of London. The private baker who persists in employing the dirty handand-arm-kneading process will soon find his customers forsaking him, and will seek a remedy in employing one of the company's machines. Of course the prejudice in the trade will have to be broken down, and this will take time. In the meantime, such of our readers as do not inhabit the localities we have named, will do well to inspect the company's family dough-making machines and fireclay ovens, which will bake bread in front of a good kitchen fire. There is one part of the company's method of bread-making that we must, in parting, take exception to, and we do so without hesitation, inasmuch as the remedy can be found by the exercise of a little of the ingenuity which has been brought to bear on the other portions of their machinery. A theoretically pure loaf ought not to be touched by human fingers until it reaches the home of the consumer. In the company's works, as soon as the dough leaves the fermenting trough, it is fashioned into loaves by the assistants. The public are so accustomed to the shape of the ordinary household loaf, that no other would be acceptable. Square bricks serve very well for sandwiches, and "cottages' for people possessed with perfect teeth, but will not do for general purposes. In these days, when tiles and drain-pipes of the most complicated forms are made by machinery, we can see no reason why the ordinary household loaf should not be made by mechanical means.

"

In conclusion, let us advise the company most strongly to have nothing to do with testimonials from the numerous adulteration-mongers, from whom, we have no doubt, they have long since received applications to analyse their bread. If their bread is good-and the samples we have tasted were excellent-the public will soon find it out, and bestow on them the best of testimonials- a large trade; while fulsome letters from half-a-dozen "chemical and microscopical analysts," with half the alphabet added to their names, can only bring suspicion on their wares, and make sensible people chary of dealing with them. If "good wine needs no bush," what shall we say of that still greater rarity-good bread? The company has commenced in a spirited and dignified manner, without puff or flaming advertisements. Let them go on so, and we venture to prophesy that their household loaves will soon become "household words."

Royal Institution.-On Monday, February 2, a General Monthly Meeting will be held at 2 o'clock. The following lectures will be delivered:-On Tuesday, February 3, at 3 o'clock, Professor Marshall, F.R S, "On Animal Mechanics." Thursday, February 5, at 3 o'clock, Dr. E. Frankland, F.R S., on "Chemical Affinity." Friday, February 6, at 8 o'clock, James Glaisher, Esq., "On Aërial Scientific Research." Saturday, February 7, at 3 o'clock, W. S. Savory, Esq., F.R.S., "On Life and Death."

ANSWERS TO CORRESPONDENTS.

All Editorial Communications are to be addressed to the EDITOR; and Advertisements and Business Communications to the PUBLISHER, at the Office, 1, Wine Office Court, Fleet Street, London, E.C.

In publishing letters from our Correspondents we do not thereby adopt the views of the writers. Our intention to give both sides of a question will frequently oblige us to publish opinions with which we do not agree.

Vol. VI. of the CHEMICAL NEWs, containing a copious Index, is now ready, price 10s. 8d., by post, 11s. 2d., handsomely bound in cloth, gold-lettered. The cases for binding may be obtained at our Office, price Is. 6d. Subscribers may have their copies bound for 2s, if sent II. are out of print. All the others are kept in stock. Vol. VII. to our Office, or, if accompanied by a cloth case, for 6d. Vols. I. and commenced on January 3, 1863, and will be complete in 26 numbers.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

Researches on the Platinum Metals,*

by WOLCOTT GIBBS, M.D. (Continued from vol. iii, page 149.)

The mass of soluble chlorides obtained by the beforementioned method contains all the platinum metals, although only traces of osmium and palladium are present; in addition, there is usually more or less insoluble matter, consisting partly of the impurities of the ore itself, and partly of undissolved oxides. A certain portion of iron also remains with the mass even after careful washing.

The washings contain a very large quantity of iron, a little ruthenium, in the form of bichloride of ruthenium and potassium, and possibly a trace of palladium. When the washing with chloride of potassium has been carefully executed with a cold and saturated solution, the quantity of ruthenium dissolved is too small to be worth separating. It only remains, therefore, to separate the metals in the mass of mixed double chlorides. Platinum and iridium exist in this mass in the form of bichlorides, as PtCl,,RC and IrCl2,KC1; ruthenium is present partly as sesquichloride, and partly as bichloride, Ru2,Cl3,2 KCÍ and RuCl,,KCI; rhodium appears to be present only as sesquichloride, Rh,Cl3.3 KCI, so far, at least, as it is possible to determine. The separation of these metals from each other is a problem of no ordinary difficulty.

Of the methods which have been proposed for this purpose, I have no hesitation in saying that that of Claus is the only one which yields the different metals in a state of purity. In fact, after a long and laborious study of the subject, I believe that no other chemist has worked with pure preparations of iridium and rhodium, the descriptions even of Berzelius applying only to mixtures of isomorphous salts in various proportions. In addition, the discovery of ruthenium by Claus rendered a complete revision of the subject necessary. Such a revision Claus has himself given in his elaborate and most valuable memoir already cited. For the details of Claus's process I must refer to his paper. In principle his method consists in separating osmium and ruthenium by fusion with a mixture of caustic potash and saltpetre; cold water then dissolves out osmate and ruthenate of potash. The residual mass consists chiefly of the oxides of iridium, rhodium, and platinum. These, after distillation with aqua regia, are brought into the form of double chlorides with ammonium, the iridium reduced to sesquioxide by means of sulphydric acid, and the platinum separated from the other two metals by washing with a strong solution of sal-ammoniac. The

From the American Journal of Science, vol. xxxiv., page 341. ↑ "Beiträge zur Chemie der Platin-metalle." Dorpat, 1854.

filtrate from the chlorplatinate of ammonium contains iridium and rhodium as sesquichlorides; the iridium is converted by chlorine and nitric acid into bichloride, and the insoluble chloro-iridate of ammonium separated by filtration from the soluble rhodium salts. This method has given excellent results in the hands of its author, but is not free from objection, the chief difficulty lying, iridium. The ruthenium salt, Ru,Cl,,2 KCl, is scarcely in my opinion, in the separation of ruthenium from to be distinguished in appearance from the iridium salt bility in water and in solutions of chloride of potassium IrCl, KCl; it possesses about the same degree of soluand ammonium. By the action of reducing agents, the sesquichloride of ruthenium is reduced, apparently, to a protochloride, the double salts of which, like Ir,Cl2,3KCI agents readily convert the protochloride of ruthenium and Ir2Cl3,3NH,Cl, are quite soluble in water. Oxidising into sesquichloride, which is again precipitated, in Claus's The portion of ruthenium which exists in the mass of process, with IrCl,,KCl, in the form of Ru2Cl3,2 KCl. double chlorides, in the form of RuCl,,KCl, may be easily and almost completely removed by repeated and careful washings with a cold and strong-but not saturated-solution of chloride of potassium, in which the salt, RuCl2,KCl, is soluble, while the other double chlorides remain undissolved. ruthenium dissolved in washing out the sesquichloride of The small quantity of iron may be recovered by precipitating the iron carefully with a solution of carbonate of potash, adding a slight excess of chlorhydric acid to the filtrate, and evaporating to dryness, when the ruthenium salt remains Claus's process, however, this method is of little use, mixed with a great excess of chloride of potassium. In since the greater part of the ruthenium is removed in the form of ruthenate of potash, while another portion remains as Ru2,Cl3,2KCl, insoluble in chloride of potassium.

fact, that the rhodium salt, Rh Cl3,3NH4Cl, is quite Another difficulty in Claus's process arises from the insoluble in a strong solution of chloride of ammonium, while a weak solution of the same salt dissolves a considerable portion of the iridium and ruthenium salts, IrCl2,KCl and Ru2Cl3,2KCl.

of RuCl-from iridium by adding a few drops of Claus's method of separating ruthenium-in the form ammonia to the neutral solution, and boiling so as to precipitate Ru2O3+xHO, gives good results when the iridium present, but not otherwise. Small quantities of quantity of ruthenium is large in proportion to the ruthenium cannot be separated at all by this process, lutely free from ruthenium by boiling. For these reasons, nor have I in any case been able to obtain iridium absowhile doing full justice to the extraordinary skill and success of the Russian chemist, I have still thought the problem of the complete separation of the metals of the platinum group worthy of a new investigation.

The method which I now use consists essentially in